Despite concerted efforts in changing lifestyles and the use of new pharmacologic approaches to lower plasma cholesterol concentrations (the main risk factor), cardiovascular disease continues to be the principal cause of death in the United States, Europe and much of Asia. Atherosclerosis in particular, is a chronic inflammatory disease involving the walls of large and medium-sized elastic and muscular arteries and can lead to ischemia of the heart, brain, intestine or extremities, resulting in infarction. While our recent work has clearly established the presence of Wnt5a in the macrophage rich regions of murine and human atherosclerotic tissue, the role of Wnt5a in the pathogenesis of atherosclerosis has not been characterized, and the source(s) of Wnt5a has (have) not been determined. Our long term goal is to understand the role of Wnt5a signaling as well as the crosstalk between this signaling pathway and Toll-Like Receptor-4 (TLR-4), another important signaling pathway involved in atherosclerosis. Our encouraging preliminary data, coupled with data from other laboratories has led us to hypothesize that Wnt5a is involved in the development and progression of ATH. We will test this hypothesis by accomplishing the following specific aims: 1. To characterize the expression of Wnt5a, and its receptors Fzd 5, 4 and 2 and Ror2 in atherosclerotic lesions isolated from ApoE-/- mice and human carotid plaques. 2. To determine if stimulation of TLR-4 signaling through ox-LDL elicits Wnt5a expression in macrophages. 3. To determine if Wnt5a induces and/or augments the proliferation and/or migration of human coronary artery smooth muscle cells (CASMC). Both in vivo and in vitro approaches involving immunostaining, in situ hybridization, RT-PCR and western-blots, in atherosclerotic lesions of ApoE-/- mice, a well-accepted murine model of ATH, and human carotid artery samples obtained from patients undergoing endarterectomy, will be used to study these aims. The results from this project will provide important information about the cellular and molecular mechanisms involved in the pathogenesis of atherosclerosis, which in turn will help in the development of new therapeutic strategies. In addition, the project will provide ample biomedical and clinical research opportunities to the undergraduate, graduate and medical students involved in various aspects of the research plan, thus fulfilling the objectives of the R15 grant mechanism. PUBLIC HEALTH RELEVANCE: Atherosclerosis is a high prevalent chronic disease in the United States, with a striking impact on public health. Currently, there is no specific treatment to curtail its development. The long term goal of the proposed project is to understand the pathogenic mechanisms involved in this disease;the results obtained, we hope, will provide a better understanding of this condition and help in the development of new strategies for treatment.